<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 100px;
            height: 100px;
            background-color: pink;
        }
        .box::before{
            display: inline-block;
            content: '';
            width: 10px;
            height: 10px;
            background-color: red;
        }
        .box::after{
            display: inline-block;
            content: '';
            width: 10px;
            height: 10px;
            background-color: red;
        }
    </style>
</head>
<body>
    <div class="box">
1
    </div>
    
</body>
</html>